Giant rheumatoid synovial cyst of the hip joint: diagnosed by MRI.
D Patkar, J Shah, S Prasad, T Patankar, S Gokhale, A Krishnan, J Limdi
Department of Radiology, Dr. Balabhai Nanavati Hospital, Mumbai, India., India
Department of Radiology, Dr. Balabhai Nanavati Hospital, Mumbai, India.
Synovial cysts are commonly found in the knee joint. Hip Joint is an infrequent site for formation of synovial cysts. The features of a large, synovial cyst on magnetic resonance imaging, occurring in the hip joint, are described.
|How to cite this article:|
Patkar D, Shah J, Prasad S, Patankar T, Gokhale S, Krishnan A, Limdi J. Giant rheumatoid synovial cyst of the hip joint: diagnosed by MRI. J Postgrad Med 1999;45:118-9
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Patkar D, Shah J, Prasad S, Patankar T, Gokhale S, Krishnan A, Limdi J. Giant rheumatoid synovial cyst of the hip joint: diagnosed by MRI. J Postgrad Med [serial online] 1999 [cited 2022 Dec 1 ];45:118-9
Available from: https://www.jpgmonline.com/text.asp?1999/45/4/118/334
Synovial cysts occur secondary to traumatic, degenerative or inflammatory conditions. Synovial cysts represent abnormal distension of bursae, which communicate with the joint. The popliteal region is the commonest site of synovial cysts. Giant synovial cysts are typically due to rheumatoid arthritis; other causes being trauma, and synovial pseudoarthrosis,.
A fifty-year-old man presented with a painless swelling in his right thigh, which was gradually progressive over five months. He was being treated with steroids for severe, rheumatoid arthritis of the hands and feet for the past three years. Clinical examination revealed generalized swelling involving the right upper thigh and significant restriction of hip joint movement. Laboratory investigations were normal except for raised ESR (45mra/hr). Sonogram of the thigh showed a large, unilocular, cystic lesion with no internal echoes. Plain radiograph of pelvis with both hip Joints showed erosive, articular changes and Joint effusion in the right hip Joint. Paracentesis of the fluid yielded sterile, inflammatory fluid with abundant lymphocytes and cellular debris. Magnetic resonance imaging (MRI) of the region demonstrated a large, bilobed, cystic lesion predominantly in the posterior aspect of the thigh and gluteal region [Figure:1]. The cyst which was hypointense on Tl WI and hyperintense on T2WI, communicated with the ilio-psoas bursa through the hip joint [Figure:2]. The cyst was resected in toto and synovium marsupialised. Histopathological examination confirmed the synovial nature of the cyst, which had a dense collagenous wall.
Synovial cysts constitute para-articular fluid collections lined by synovial membrane, which may or may not communicate with the adjacent Joint. Typical aetiologic factors include rheumatoid arthritis, seronegative spondyloarthropathies, osteoarthrosis and crystal deposition diseases,. However, any long-standing or large effusion of any cause can give rise to synovial cysts. Synovial cysts usually manifest as periarticular swellings. Synovitis results in formation of reactive, inflammatory fluid, which raise intraarticular pressure. Increased intraarticular pressure is detrimental to synovial perfusion and may cause joint instability. Formation of synovial cysts constitutes an effective decompressive mechanism to relieve raised intra-articular pressure and its attendant sequelae. Unilateral egress of fluid from the inflammed joint, (especially noticed in the knee joint) contribute to cyst growth.
Symptomatic cysts may cause pain or limitation of joint mobility. Uncommonly, they may cause compression of the neighbouring neurovasular structures. Van Mourik et al reported a case of synovial cyst of the hip joint presenting as deep venous thrombosis, secondary to compression of the femoral/iliac vein. Acute rupture of the cysts may occur infrequently which may dissect into adjacent soft tissues. Secondary infection of the cysts may lead to abscess formation.
Synovial cysts can be unilocular or multilocular with a relatively acellular, fibrous wall. Rarely, dystrophic calcification of the wall can be identified. Plain radiographs, arthrography, ultrasound and computed tomographic scan have been used in evaluation of the synovial cysts. However, MRI is considered the best imaging modality for optimal delineation of the extent of the cyst and assessment of the associated causative disorder. It is found that the hip joint is often affected by rheumatoid arthritis in patients who are on steroid medication. Our patient was on steroid therapy for three years for rheumatoid disease of his hands and feet. Steroid use may have contributed to localization of the disease in the hip joint. In addition, steroids caused masking of classic, inflammatory changes at the hip joint and the patient presented with a large, painless thigh mass. In conclusion, synovial cysts may enlarge considerably to manifest as mass lesions at locations away from the joint. MRI, on account of its multiplanar imaging capabilities and superior soft tissue resolution, enables us to establish definitive diagnosis. MRI is useful to identify the synovial origin of the lesion, determine its complete extent and recognize adjacent vital neurovasular structures.
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